1. Field of the Invention
The present invention generally relates to printed board units, and more particularly to a printed board unit which includes a large scale integration (LSI) package of a land grid array (LGA) type mounted on a printed board with an LGA socket interposed therebetween, and forms a server that is an information processing and communication facility.
A printed board unit forming a server is plugged into a motherboard in consideration of repairs in the event of a failure, and an LSI package is replaceably mounted on a printed board.
In the server, repairs are made with a printed board unit being removed from the server. During the repairs, the server operates with a reduced processing capacity compared with its normal state since the printed board unit is removed from the server. Therefore, it is desirable that the repairs should be made so quickly that a period for which the server operates with the reduced capacity compared with its normal state becomes as short as possible.
Further, like the above-described repairs, the additional installation of an LSI package on the printed board is also performed with a printed board unit being removed from the server. Therefore, it is also desirable that the additional installation of the LSI package should be quickly performed.
Moreover, it is desirable that the repairs should be made and the additional installation should be performed with the lowest possible costs.
2. Description of the Related Art
FIGS. 1 and 2 each show a conventional printed board unit 10. The printed board unit 10 includes an LGA-type LSI package 20 mounted on a printed board 11 with an LGA socket 30 interposed therebetween. A stiffener 40 is provided on the lower surface of the printed board 11 with an insulating sheet 45 interposed therebetween, and a heat transfer plate 41 that doubles as a cooling fin is provided on the upper surface of the LSI package 20. The printed board unit 10 further includes nuts 42, which are tightened so that the heat transfer plate 41 presses the LSI package 20 onto the printed board 11 through a heat transfer sheet 46 by coiled springs 43. Each of lands 21 of the LSI package 20 is electrically connected to a corresponding one of lands 12 formed on the printed board 11 via a corresponding one of contacts 31 of the LGA socket 30.
The printed board unit 10 is mounted on a motherboard by being plugged thereinto and is incorporated into a server.
Here, a description will be given of repairs in the event of a failure of the LSI package 20.
The repairs are made in the following procedure. In step 1, the printed board unit 10 is removed outside from the server. In step 2, at the site, the nuts 42 are loosened and removed, and the heat transfer plate 41 is pulled off the bolts 40a of the stiffener 40 so that the LSI package 20, the LGA socket 30, and the heat transfer plate 41 are apart from one another. In step 3, the faulty LSI package 20 is replaced with a new LSI package. In step 4, the LSI socket 30 is positioned on the printed board 11. In step 5, the new LSI package is positioned on the LSI socket 30. In step 6, the heat transfer plate 41 is combined with the stiffener 40 and the coiled springs 43 are fitted to the bolts 40a before the nuts 42 are tightened. In step 7, the printed board unit 10 is inserted into the server.
Repairs are also made in the above-described procedure in the event of a failure of the LGA socket 30.
Positioning the new LSI package on the LGA socket 30 requires accuracy, and is troublesome and relatively time-consuming. Therefore, the repairs of failures of the LSI package 20 and the LGA socket 30 are relatively time-consuming.
The additional installation of an LSI package also requires positioning the LSI package on an LGA socket, and therefore, is relatively time-consuming.
At some sites, dust attaches to the lands 21 of the LSI package 20 and the contacts 31 of the LGA socket 30 while the LSI package 20 and the LGA socket 30 are apart from each other so that the reliability of electrical connection between the LSI package 20 and the LGA socket 30 may be impaired.
In the event of a failure of an LSI package or an LGA socket, a new printed board unit may be fitted into the server after a printed board unit including the faulty LSI package or LGA socket is removed from the server, which method dispenses with the removal of the faulty LSI package or LGA socket.
The above-described method dispenses with the replacement of the faulty LSI package or LGA socket, thus realizing quick replacement of a faulty component. However, in order to realize this method, it is necessary to prepare a new printed board unit for replacement for each printed board unit, thus increasing the costs of spare components.
Similarly, in the case of the additional installation of an LSI package, it is necessary to prepare a new printed board unit for the additional installation, thus increasing the costs of spare components.
It is a general object of the present invention to provide a printed board unit in which the above-described disadvantages are eliminated.
A more specific object of the present invention is to provide a printed board unit which includes a semiconductor device unit as a replacement unit so as to be repaired and reproduced easily in a short time in the event of a failure only by replacing the semiconductor device unit.
The above objects of the present invention are achieved by a printed board unit including a printed board including lands thereon, a semiconductor device unit, and an attachment mechanism for attaching the semiconductor device unit to the printed board, wherein the semiconductor device unit includes: a heat transfer member; a semiconductor device including first and second surfaces parallel to each other, the first surface having lands thereon; and a socket including contacts protruding from first and second surfaces of the socket, the first and second surfaces being parallel to each other, wherein the semiconductor device and the socket are attached to the heat transfer member so that the second surface of the semiconductor device opposes the heat transfer member, and the lands of the semiconductor device are electrically connected to the lands of the printed board unit via the contacts of the socket.
According to the above-described printed board unit, the semiconductor device unit is a replacement unit. In the event of a failure of the semiconductor device, repairs are completed only by removing the semiconductor device unit including the faulty semiconductor device from the printed board unit and replacing the semiconductor device unit by a prepared new semiconductor device unit. Therefore, the positioning of the semiconductor device on the socket is unnecessary. Thus, the printed board unit is repaired in a shorter time than a conventional printed board unit, which requires a semiconductor device and a socket to be apart from each other for repair.